On the day of his daughter's birthday, William "D-Fens" Foster is trying to get to the home of his estranged ex-wife to see his daughter. His car breaks down, so he leaves his car in a traffic jam in Los Angeles and decides to walk. He goes to a convenience store and tries to get some change for a phone call, but the Korean owner does not oblige, tipping Foster over the edge. The unstable Foster, so frustrated with the various flaws he sees in society, begins to psychotically and violently lash out against them.